Backpack



FIG. 1 is a front side perspective view of the backpack showing my new design;

FIG. 2 is a rear right side perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a left side elevational view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof.

The broken lines showing stitching form no part of the claimed design. All other broken lines show portions of the backpack that form no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 